Aside from its unique design, The Plug doesn't have many standout features. Although the 'phones have a tangle-prone, dual-sided cord (one cord is attached to each earpiece), Koss doesn't supply a carrying case. The Plug does include four sets of various-size foam earpieces that can be interchanged to facilitate a snug fit in virtually any pair of ears. The hollow, hard plastic sound tubes in the center of the squishy earpieces tended to unpleasantly scratch our ear canals whenever we put on or adjusted The Plug.

The Plug's 4-foot cord is long enough to comfortably connect with a portable audio player, but it's short enough not to cause much tugging during workout sessions. We took The Plug for a 30-minute treadmill run and were pleasantly surprised by the results. Only once during our jaunt did The Plug pop out of our ears. In comparison, it's almost impossible to run with standard, loose-fitting earbuds such as Sony's MDR-E827Gs ($19.99 list).

A highly efficient (112 dB) headphone set, The Plug had no problem playing loud even when connected to our underpowered portable MP3 player. Tracks such as Paul Oakenfold's "Essential Mix at Home in Ibiza" sounded smooth and were free of the overblown treble and brash midrange exhibited by many competing earbuds. Bass response was comparatively tight and punchy.

Overall, The Plug sounds better than most 'phones in the same low price range. What's more, The Plug is one of the few earbud headphone models that won't constantly fall out of your ears during jarring activities. If you can get past the occasionally invasive feeling of the in-ear sound tubes, you'll probably dig The Plug. But if you can afford to pay more, check out Sony's MDR-EX71SL earbuds, which offer better sound and a more comfortable fit.